1. Field
The present invention relates to a method for preparing nano/micro array and acquiring nanopatterning image using an atomic force microscope (AFM), and more specifically, is to an apparatus for preparing nanopositioning substrate using dip pen nanolithography with a single tip or multiple tips using ATM, and a method of using the apparatus for preparing a nanopositioning substrate and a method for preparing a nano/micro array and acquiring a nanopatterning image using the same.
2. Discussion of the Background
Conventional dip-pen nanolithography-applied researches have worked on the issue of immobilizing DNA, proteins, and antibodies on a substrate surface to form a nanoarray, and maintaining activity of the biopolymer immobilized on the surface.
However, as well known, the biopolymers such as DNA or proteins, when used as ink, are less interactive with substrate and have deteriorated immobilization efficiency.
Further, despite some advantages of preparing biochip using dip-pen nanolithography, such as increased density level (several tens of million times greater density compared to currently available biochip system), the disadvantageous need for the preparation of inkwells in the amount and size corresponding to the AFM tips and for loading independent contents in the respective nano-wells to load independent contents on the respective ATM tips, causes the actual application to be excessively costly. As a result, while there are many reports on experiments where one type of protein or DNA is repeatedly written, the practical nanoscale biochip has not been achieved so far.
Further, the conventional method for the preparation of multiple tips mainly include preparing approximately 55,000 multiple tips, or preparing nanoarrays using only one ink solution for the 55,000 tips, and yet, layering a variety of contents has not been accomplished so far.
Meanwhile, apart from the above, research has been carried out on the preparation of cantilever array integrating approximately one million ATM tips, and this way of mass producing a single tip or multiple tip models can surely provide an advantage of increased is productivity of dip-pen nanolithography. However, as far as it concerns the condition to produce ten thousands of wafers, the productivity of the optical lithography is still incomparable.
In other words, even though several millions of multiple tip systems are possible, without sufficient position reproducibility, that is, without the ability of the individual AFM tips to return to original positions after pattern formation, biochips with extra high density can hardly be achieved.
However, the current technologies require that the respective spots be maintained at several μm spacing to prevent cross-contamination of the ink. For example, in the case of a bio array, the patterned individual spots are limited within at least several μm spacing, and this also has close relationship with the position reproducibility.
In the latest optical lithography nanopositioning technology which is generally applied to electronic engineering, the position reproducibility of several nanometers can be achieved with piezoelectric elements fixed to a silicon or glass substrate. In this case, the nanometer-scale position reproducibility is achieved using the alignment markers formed on the substrate and a photomask, respectively, or using the interference phenomena of the grating patterns to be more specific.
However, none has successfully incorporated the nanopositioning using AFM to a coherent process that can achieve position reproducibility from a scale of several mm2 to a scale less than several hundred nanometers.
That is, in the laboratory scale, one suggestion was to mark small marker patterns (in several dozen nanometers in size) using AFM in advance, replace with other AFM tips loaded with different ink, and find the previously marked positions (using AFM imaging) to achieve nanopatterns.
However, the above process requires as an essential process the AFM imaging to find the previously patterned markers, during which contamination of the surface having markers thereon by the ink on the AFM tip frequently occurs.
Therefore, in order to prevent problem of cross-contamination associated with the replacement of inks in the preparation of nanoarrays using several dozens to several hundreds of inks with dip-pen nanolithography using different ink molecules, it is necessary to maintain the respective nanoarrays at a spacing of several hundred nanometers and several micrometers.
To sum up, the currently available technologies still suffer greatly deteriorating efficiency in the preparation of extra high density arrays using extra high density nanoarrays with dip-pen nanolithography using AFM.
That is, generally, the substrate for the purpose of AFM is operated by a piezo-motor (taking x-axis for example, the maneuver margin ranges between several hundred nm and several hundred μm), but the position deviates from a range of several hundred nm and several hundred μm, exceeding the operating area of the piezo-motor in the process of replacing AFM tips. Accordingly, the limited position reproducibility is considered to be the main problem to be tackled with in the preparation of extra high density nanoarary.
Even if the operation is performed within the operational limit of the piezo-motor (without having to replace ATM tips), considering hysteresis, which characteristically occurs in the piezo-motor during repetitive operations, the deviation of the position by a range of several tens or hundreds of nanometers is inevitable.
Therefore, the ability to repetitiously align the AFM tips under several nanometer scale precision is considered to be the bottle neck technology to the mass production of biochips or extra high density biochips.
That is, in order to solve the problems associated with the prior art, in the mass production of biochips or preparation of extra high density biochips, an apparatus or a method is necessary, which can repetitiously align the AFM tips under several nanometer scale precision, but none has been able to provide the apparatus or method that can meet such demands.